Struct windows::core::Borrowed

#[repr(transparent)]
pub struct Borrowed<'a, T: Abi> { /* private fields */ }

A logically borrowed type that still retains the in-memory representation of the underlying type.

Note: this type is normally only used as a field to a struct. For function parameters, the Param type, which builds on top of Borrowed is used.

Borroweds can be thought of much like an Option<&T>. The reason Borrowed must be used instead of Option<&T> is because Borrowed has the same in-memory layout as Option<T>. This is necessary for FFI calls that expect a logically borrowed type that, in-memory, looks like an owned type.

It’s important to note that owned values cannot be turn into Borroweds. After all, Borrowed types are borrowed and not owned. Just as you cannot turn pass a T into function and get a &T back, you cannot pass a T into a function that ultimately expects a Borrowed<'a, T>.

Implementations

impl<'a, T: Abi> Borrowed<'a, T>

pub fn new(item: Option<&'a T>) -> Self

Create a new Borrowed value.

Normally, it is not necessary to use this function. Generally, there is a From implementation that allows you to call .into to safely create a Borrowed value.

pub fn none() -> Self

Create a new null Borrowed value.

pub fn abi(&self) -> T::Abi

Get the abi representation for this param

Note: the return value is only guranteed to be valid for the lifetime of &self

pub fn as_ref(&self) -> Option<&T>

Get an optional reference to the underlying value

Trait Implementations

impl<'a, T: Abi> Clone for Borrowed<'a, T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a, T: Abi + Debug> Debug for Borrowed<'a, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a, T, U> From<&'a U> for Borrowed<'a, T>where
    T: Abi + 'a,
    &'a U: Into<&'a T>,

fn from(item: &'a U) -> Self

Converts to this type from the input type.

impl<'a, T: Abi> From<Option<&'a T>> for Borrowed<'a, T>where
    &'a T: Into<Borrowed<'a, T>>,

fn from(item: Option<&'a T>) -> Self

Converts to this type from the input type.

impl<'a> From<bool> for Borrowed<'a, bool>

fn from(item: bool) -> Self

Converts to this type from the input type.

impl<'a> From<f32> for Borrowed<'a, f32>

fn from(item: f32) -> Self

Converts to this type from the input type.

impl<'a> From<f64> for Borrowed<'a, f64>

fn from(item: f64) -> Self

Converts to this type from the input type.

impl<'a> From<i16> for Borrowed<'a, i16>

fn from(item: i16) -> Self

Converts to this type from the input type.

impl<'a> From<i32> for Borrowed<'a, i32>

fn from(item: i32) -> Self

Converts to this type from the input type.

impl<'a> From<i64> for Borrowed<'a, i64>

fn from(item: i64) -> Self

Converts to this type from the input type.

impl<'a> From<i8> for Borrowed<'a, i8>

fn from(item: i8) -> Self

Converts to this type from the input type.

impl<'a> From<isize> for Borrowed<'a, isize>

fn from(item: isize) -> Self

Converts to this type from the input type.

impl<'a> From<u16> for Borrowed<'a, u16>

fn from(item: u16) -> Self

Converts to this type from the input type.

impl<'a> From<u32> for Borrowed<'a, u32>

fn from(item: u32) -> Self

Converts to this type from the input type.

impl<'a> From<u64> for Borrowed<'a, u64>

fn from(item: u64) -> Self

Converts to this type from the input type.

impl<'a> From<u8> for Borrowed<'a, u8>

fn from(item: u8) -> Self

Converts to this type from the input type.

impl<'a> From<usize> for Borrowed<'a, usize>

fn from(item: usize) -> Self

Converts to this type from the input type.